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United States Patent |
5,653,144
|
Fenelon
|
August 5, 1997
|
Stress dissipation apparatus
Abstract
A rotatable apparatus includes a pair of rotatable members joined by a
stress dissipating structure. The stress dissipating structure can be
employed in a gear, sprocket, clutch or the like. In one embodiment of the
present invention, antibuckling plates generally spanning between a hub
and rim define a hollow cavity. In another embodiment of the present
invention, the stress dissipating structure includes a specifically
configured sets of nodules moving the hub and rim. An additional aspect of
the present invention provides a stress dissipating structure employing
various anti-buckling plate attachment constructions. In still another
embodiment of the present invention, a uniquely sized and packaged gear,
gear housing and/or motor are employed in order to maximize output force
per pound of material efficiencies.
Inventors:
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Fenelon; Paul J. (13 Inverary, Nashville, TN 37215)
|
Appl. No.:
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545997 |
Filed:
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October 20, 1995 |
Current U.S. Class: |
74/411; 49/342; 49/349; 74/89.14; 74/89.18; 74/425; 74/447; 74/606R; 192/150; 318/474; 464/75 |
Intern'l Class: |
F16D 003/68; F16H 055/14; F16H 001/16 |
Field of Search: |
74/89.14,89.18,446,447,425,606 R
49/342,349
192/150
318/474,476
464/74,75
|
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Other References
Machine Design--Basics of Design Engineering, "Components for drivelines",
Jun. 1992, pp. 92-96.
Photographs of sunroof motor (prior to Jun. 7, 1995).
Photographs of window lift motor having three elastomeric inserts (prior to
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Photographs of window lift motor having a rim, web, hub and elastomeric
material (prior to Dec. 1, 1993).
|
Primary Examiner: Herrmann; Allan D.
Attorney, Agent or Firm: Harness, Dickey & Pierce, P.L.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. application Ser. No.
08/488,344 filed Jun. 7, 1995 which is a continuation-in-part of PCT
application Ser. No. PCT/US94/01577 filed Feb. 9, 1994 which designated
the United States as a continuation-in-part of U.S. application Ser. No.
160,544, filed Dec. 1, 1993, now issued on Sep. 26, 1995 as U.S. Pat. No.
5,452,622, which is a continuation-in-part of U.S. application Ser. No.
08/015,332, filed Feb. 9, 1993, now issued on May 3, 1994 as U.S. Pat. No,
5,307,705; this application is also directly a continuation-in-part of
U.S. application Ser. No. 160,544, filed Dec. 1, 1993, now issued on Sep.
26, 1995 as U.S. Pat. No. 5,452,622, which is a continuation-in-part of
U.S. application Ser. No. 08/015,332, filed Feb. 9, 1993, now issued on
May 3, 1994 as U.S. Pat. No., 5,307,705; all of these are incorporated by
reference herewithin.
Claims
The invention claimed is:
1. A rotatable apparatus comprising:
a hub having a section coaxial with a rotational axis;
a first annular plate projecting radially outward from said hub;
a second plate being offset from and having a plane substantially parallel
to a plane of said first plate;
an annular rim coaxially aligned with and outwardly disposed from said hub,
said rim being coupled to said first plate;
a rotational stress dissipation device being joined to said rim and to at
least one of said plates; and
a hollow and substantially annular cavity being disposed between said
plates;
said hub, rim and plates being injection molded from an inherently
lubricous polymeric material such that relative movement therebetween has
reduced friction.
2. The rotatable apparatus of claim 1 wherein:
said first plate is integrally formed as part of said hub; and
said second plate is integrally formed as part of said rim.
3. The rotatable apparatus of claim 2 wherein a section of said hub
outwardly extends from an outside face of said first plate such that said
section of said hub and at least a majority portion of said rim are
laterally offset from each other.
4. The rotatable apparatus of claim 3 further comprising:
a set of pinion gear teeth radially extending outward from said section of
said hub; and
a set of rim gear teeth radially extending outward from said rim.
5. A rotatable apparatus comprising:
a hub having a section coaxial with a rotational axis;
a first annular plate projecting radially outward from said hub;
a second plate being offset from and having a plane substantially parallel
to a plane of said first plate;
an annular rim coaxially aligned with and outwardly disposed from said hub,
said rim being coupled to said first plate;
a rotational stress dissipation device being joined to said rim and to at
least one of said plates;
a hollow and substantially annular cavity being disposed between said
plates; and
a snap-fit extending from at least one of said plates engaging a snap-fit
receptacle of at least the other of said plates.
6. A rotatable apparatus comprising:
a hub having a section coaxial with a rotational axis;
a first annular plate projecting radially outward from said hub;
a second plate being offset from and having a plane substantially parallel
to a plane of said first plate;
an annular rim coaxially aligned with and outwardly disposed from said hub,
said rim being coupled to said first plate;
a rotational stress dissipation device being joined to said rim and to at
least one of said plates;
a hollow and substantially annular cavity being disposed between said
plates; and
a substantially cylindrical leg inwardly extending from said inside face of
one of said plates, said leg being concentrically and coaxially aligned
with said rotational axis, said leg separating said rotational stress
dissipating member from said hollow cavity.
7. A rotatable apparatus comprising:
a hub having a section coaxial with a rotational axis;
a first annular plate projecting radially outward from said hub;
a second plate being offset from and having a plane substantially parallel
to a plane of said first plate;
an annular rim coaxially aligned with and outwardly disposed from said hub,
said rim being coupled to said first plate;
a rotational stress dissipation device being joined to said rim and to at
least one of said plates;
a hollow and substantially annular cavity being disposed between said
plates;
a gear housing having a cup shape defined by a substantially cylindrical
interior wall, a substantially cylindrical exterior wall and a
substantially annular bottom wall;
said interior wall of said gear housing acting as a rotational bearing
surface for said hub; and
an inner surface of said gear housing interior wall located closest to said
rotational axis defining a substantially cylindrical opening with a
diameter relatively larger than a radial distance measured between said
hub and said rim along one side of said rotatable apparatus.
8. A rotatable apparatus comprising:
a hub having a section coaxial with a rotational axis;
a first annular plate projecting radially outward from said hub;
a second plate being offset from and having a plane substantially parallel
to a plane of said first plate;
an annular rim coaxially aligned with and outwardly disposed from said hub,
said rim being coupled to said first plate;
a rotational stress dissipation device being joined to said rim and to at
least one of said plates;
a hollow and substantially annular cavity being disposed between said
plates;
said rotational stress dissipation device including:
nodule means depending from at least one member taken from the group
consisting of: said hub, said first plate, said second plate and said rim;
and
resilient means for reducing different rotational movements between said
hub and said rim, said resilient means acting against said nodule means,
said resilient means being clear of an annular area disposed between at
least one of said plates and said rim.
9. A rotatable apparatus comprising:
a hub having a section coaxial with a rotational axis;
a first annular plate projecting radially outward from said hub;
a second plate being offset from and having a plane substantially parallel
to a plane of said first plate;
a rim coaxially aligned with and outwardly disposed from said hub, said rim
being coupled to said first plate;
a rotational stress dissipation device being joined to said rim and to at
least one of said plates; and
a leg laterally extending from a middle segment of one of said plates and
being directly affixed to the other of said plates.
10. The rotatable apparatus of claim 9 wherein said first plate rotatable
moves with said hub and said second plate rotatably moves with said rim,
said first plate is coupled to said rim but can rotatably move relative to
said rim, said first plate can rotate relative to said second plate and is
not rotatably limited by affixation of said leg therebetween.
11. The rotatable apparatus of claim 10 further comprising:
a first snap-fit attachment joining said leg of said one of said plates to
said other of said plates; and
a second snap-fit joining said first plate to said rim.
12. The rotatable apparatus of claim 9 wherein said leg of said one of said
plates has a substantially cylindrical configuration concentric with said
rim with said stress dissipating structure disposed within an annular
channel defined between said plates and between said rim and said leg.
13. The rotatable apparatus of claim 12 further comprising:
a set of pinion gear teeth radially extending outward from said section of
said hub; and
a set of rim gear teeth radially extending outward from said rim.
14. The rotatable apparatus of claim 9 wherein said rotational stress
dissipation device includes:
nodule means depending from at least one member taken from the group
consisting of: said hub, said first plate, said second plate and said rim;
and
resilient means for reducing different rotational movements between said
hub and said rim, said resilient means acting against said nodule means,
said resilient means being clear of an annular area disposed between at
least one of said plates and said rim.
15. A rotatable apparatus comprising:
an inner member including a hub;
a first set of nodules extending radially outward from said inner member,
each of said first set of nodules having a proximal end located closest to
a rotational axis and having an opposite distal end, said proximal end of
each of said first set of nodules having a relatively constricted
rotational direction dimension as compared to an expanded rotational
direction dimension at said distal end with first and second tapered
surfaces extending between said proximal and distal ends;
an outer member including a rim;
a second set of nodules radially extending inward from said outer member,
each of said second set of nodules having a proximal end located closest
to said rim and having an opposite distal end, said distal end of each of
said second set of nodules having a relatively constricted rotational
direction dimension as compared to an expanded rotational direction
dimension at said proximal end with third and fourth tapered surfaces
extending between said proximal and distal ends; and
resilient means for reducing rotational differential movement disposed
between said first and second sets of nodules, said resilient means also
being disposed between said distal ends of at least one set of said
nodules and at least an adjacent one of said members.
16. The rotatable apparatus of claim 15 further comprising a first set of
geared teeth outwardly extending from said rim.
17. The rotatable apparatus of claim 16 further comprising a second set of
geared teeth extending from said hub.
18. The rotatable apparatus of claim 15 wherein said resilient means
includes a shock absorbing and resilient elastomeric material disposed
between each adjacent pair of said sets of nodules, the amount of taper of
each of said nodules and the amount of elastomeric material ("E") disposed
between each pair of adjacent nodules can be substantially characterized
by the following formula:
##EQU2##
where E.sub.2 is a rotational direction dimension between said proximal
end of one of said second set of nodules and said distal end of an
adjacent one of said first set of nodules;
E.sub.1 a rotational direction dimension between said distal end of said
one of said second set of nodules and said proximal end of said adjacent
one of said first set of nodules; and
D.sub.2 is a diameter of said rim teeth and D.sub.2 is a diameter of said
hub teeth;
whereby generally uniform strain is imparted upon said elastomeric material
during deformation due to differing rotational movement between said rim
and said hub.
19. A rotatable apparatus comprising:
an inner member including a hub;
a first set of nodules extending radially outward from said inner member,
each of said first set of nodules having a proximal end located closest to
a rotational axis and having an opposite distal end, said proximal end of
each of said first set of nodules having a relatively constricted
rotational direction dimension as compared to an expanded rotational
direction dimension at said distal end with first and second tapered
surfaces extending between said proximal and distal ends;
an outer member including a rim;
a second set of nodules radially extending inward from said outer member,
each of said second set of nodules having a proximal end located closest
to said rim and having an opposite distal end, said distal end of each of
said second set of nodules having a relatively constricted rotational
direction dimension as compared to an expanded rotational direction
dimension at said proximal end with third and fourth tapered surfaces
extending between said proximal and distal ends; and
resilient means for reducing rotational differential movement disposed
between said first and second sets of nodules;
wherein said inner member includes a first annular anti-buckling plate
securely affixed to said hub and being disposed laterally outward of said
sets of nodules.
20. The rotatable apparatus of claim 19 wherein said outer member further
includes a second annular anti-buckling plate securely affixed to said rim
and being disposed laterally outward of said sets of nodules.
21. A stress dissipation apparatus comprising:
an armature housing having a longitudinal dimension and transverse
dimensions;
a rotatable armature with wire windings being internally disposed and
journalled within said armature housing;
at least one permanent magnet being internally disposed within said
armature housing adjacent to said armature;
a rotatable armature shaft extending from said armature, a gear segment
being disposed along a portion of said armature shaft; and
a gear including a hub, a rim and means for dissipating rotational movement
differences between said hub and said rim, said hub having a set of geared
teeth, said rim having a set of geared teeth for enmeshing with said gear
segment;
wherein said rim teeth have an outer diameter less than one and one-half
times an outer diameter of said hub teeth whereby a relatively smaller
motor can be employed to drive a relatively larger diameter gear, as
compared to conventional motors and gears, such that improved driving
output forces per pound of material efficiencies are achieved.
22. The stress dissipation apparatus of claim 21 wherein said means for
dissipating rotational movement differences includes:
a first set of nodules moving with said hub;
a second set of nodules moving with said rim; and
a resilient member disposed between adjacent pairs of said sets of nodules.
23. The stress dissipation apparatus of claim 22 wherein said resilient
member is an elastomeric material.
24. The stress dissipation apparatus of claim 21 wherein said gear further
includes:
a first antibuckling plate spanning between said hub and said rim; and
a second antibuckling plate spanning between said hub and said rim.
25. The rotatable apparatus of claim 21 further comprising:
a gear housing having a cup shape defined by a substantially cylindrical
interior wall, a substantially cylindrical exterior wall and a
substantially annular bottom wall;
said interior wall of said gear housing acting as a rotational bearing
surface for said hub; and
an inner surface of said gear housing interior wall located closest to said
rotational axis defining a substantially cylindrical opening with a
diameter relatively larger than a radial distance measured between said
hub and said rim along one side of said rotatable apparatus.
26. The stress dissipation apparatus of claim 21 further comprising a
window lift mechanism for an automotive vehicle being movably driven by
rotation of said hub.
27. A gear comprising:
a primary hub having a set of outwardly extending teeth;
an auxiliary hub being offset and separately formed in relation to said
primary hub;
a rim concentrically surrounding said auxiliary hub; said rim being
coaxially aligned with said primary hub; and
said auxiliary hub rotating in concert with said rim but being adapted to
be rotatable a different amount than said primary hub.
28. The gear of claim 27 further comprising means for reducing rotational
differential movement coupling said rim to primary hub.
29. The gear of claim 28 wherein said means for reducing rotational
differential movement includes:
a first set of nodules moving with said primary hub;
a second set of nodules moving with said rim; and
resilient means disposed between said sets of nodules.
30. The gear of claim 27 further comprising at least one curved projection
inwardly extending from at least one of said hubs acting as a bearing
surface against an adjacent gear housing.
31. An apparatus comprising:
an armature housing having a longitudinal dimension and transverse
dimensions;
a rotatable armature with wire windings being internally disposed and
journalled within said armature housing;
at least one permanent magnet being internally disposed within said
armature housing adjacent to said armature;
a rotatable armature shaft extending from said armature, a gear segment
being disposed along a portion of said armature shaft;
a driven gear including a hub and a rim, said hub having a driving
interface, said rim having a set of geared teeth for enmeshing with said
gear segment;
a gear housing having a cup shape defined by a substantially cylindrical
interior wall, a substantially cylindrical exterior wall and a
substantially annular bottom wall;
said interior wall of said gear housing acting as a rotational bearing
surface for said hub; and
an inner surface of said gear housing interior wall located closest to said
rotational axis defining a substantially cylindrical opening with a
diameter relatively larger than a radial distance measured between said
hub and said rim along one side of said driven gear;
wherein said rim has an outer diameter less than one and one-half times an
outer diameter of said hub driving interface whereby a relatively smaller
motor can be employed to drive a relatively larger diameter gear, as
compared to conventional motors and gears.
32. The apparatus of claim 31 further comprising a polymeric annular plate
spanning between members including said hub and said rim, at least one
edge of said plate being movable relative to at least one of said members,
said plate having a substantially uniform thickness dimension less than a
radius dimension of said plate.
33. The apparatus of claim 31 further comprising a window lift mechanism
for an automotive vehicle being movably driven by rotation of said driving
interface engaged therewith.
34. The apparatus of claim 31 further comprising means for dissipating
rotational movement differences between said hub and said rim.
35. The apparatus of claim 31 further comprising a web integrally formed as
part of and rotationally joined to said hub and said rim.
36. The gear of claim 31 wherein said armature shaft rotates at a speed
less than 4,000 revolutions per minute and said rim rotates at a speed
less than 80 revolutions per minute while hub driving interface torque of
at least 100 inch-pounds is produced.
37. In combination, an automotive vehicle electric dc motor and gear system
comprising:
an armature housing having a longitudinal dimension and transverse
dimensions;
a rotatable armature with wire windings being internally disposed and
journalled within said armature housing;
at least one permanent magnet being internally disposed within said
armature housing adjacent to said armature;
a rotatable armature shaft extending from said armature, a gear segment
being disposed along a portion of said armature shaft;
a gear including a hub, a rim and a web spanning between said hub and said
rim, said rim having a set of geared teeth for enmeshing with said gear
segment of said armature shaft;
a gear housing having a cup shape defined by a substantially cylindrical
interior wall, a substantially cylindrical exterior wall and a
substantially annular bottom wall;
said interior wall of said gear housing acting as a rotational bearing
surface for said hub;
an inner surface of said gear housing interior wall located closest to said
rotational axis defining a substantially cylindrical opening with a
diameter relatively larger than a radial distance measured between said
hub and said rim along one side of said rotatable apparatus; and
said hub, rim and web being formed to rotate as a single piece;
wherein said rim has an outer diameter less than one and one-half times an
outer diameter of said hub whereby a relatively smaller motor can be
employed to drive a relatively larger diameter gear, as compared to
conventional motors and gears.
38. The combination of claim 37 further comprising a current sensor
electrically connected to a commutator rotating with said armature shaft,
said current sensor causing said motor to be deenergized if motor torque
suddenly increases.
39. The combination of claim 37 wherein said armature shaft rotates at a
speed less than 4,000 revolutions per minute and said gear rotates at a
speed less than 80 revolutions per minute while pinion teeth torque of at
least 100 inch-pounds is produced.
40. In combination, an automotive vehicle electric dc motor and gear system
comprising:
an armature housing having a longitudinal dimension and transverse
dimensions thereby defining an inner volume;
a rotatable armature with wire windings being internally disposed and
journalled within said armature housing;
at least one permanent magnet being internally disposed within said
armature housing adjacent to said armature;
a rotatable armature shaft extending from said armature, a gear segment
being disposed along a portion of said armature shaft;
a driven gear including a hub, a rim and a member spanning between said hub
and said rim, said rim having a first set of geared teeth for enmeshing
with said gear segment of said armature shaft; and
a pinion gear rotating with said hub and having a second set of geared
teeth;
wherein said driven gear has an outer diameter that is less than one and
one-half times that of an outer diameter of said pinion gear and the
volume of said armature housing divided by said outer diameter of said
driven gear is less than two inches squared.
41. The combination of claim 40 further comprising a current sensor
electrically connected to a commutator rotating with said armature shaft,
said current sensor causing said motor to be deenergized if motor torque
suddenly increases.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to rotatable apparatuses and specifically
to a rotatable apparatus having a pair of rotatable members joined by a
stress dissipating structure and a rotatable apparatus having enlarged and
decreased rpm driven and pinion gear portions for use with a worm drive
and a smaller motor.
The primary function of a gear is to transmit power from a power generating
source to an operating device. This is achieved through the intermeshing
and continuity of action between the teeth of a driving gear which is
associated with the power source and the teeth of the mating gear which is
associated with the operating device. Since a gear is a rotating body, a
state of dynamic equilibrium must be attained. Therefore, to be in dynamic
equilibrium all of the reactions from the rotating gear must be
neutralized by equal and opposite forces supporting the gear shaft.
Traditional gear design comprises a central hub, a web extending radially
outward therefrom which is, in turn, peripherally bordered by an integral
radial rim having geared teeth thereupon. Gear failure can occur if
manufacturing tolerances, material type, and gear design are not matched
to the service application. Furthermore, since gears have historically
been manufactured from a single homogeneous material, the bulk rigidity
and strength of the web is generally greater than or equal to that of the
hub and rim. Thus, torsional stresses created through start-up, shut-down,
overload, or through cyclical fatigue are localized in the teeth and hub
areas. As a result, gears typically fail at the root of the teeth or in
the hub region. Such failures include excessive wear, plastic flow or
creep, tooth bending fatigue, contact fatigue (pitting and spalling),
thermal fatigue, tooth bending impact, tooth shear, tooth chipping, case
crushing, torsional shear and stress ruptures. Many of these failures are
due primarily to overload, cycling fatigue, and/or start-up and shut-down
rotational shock referenced above that is especially prevalent in gears
that perform in non-constant rotation service applications.
Additionally, most, if not all, motors and gears used in automotive window
lift applications tend to be rather large in a transverse direction (i.e.,
perpendicular to the armature shaft rotational axis) primarily due to the
inefficiently constructed conventional driven gear coupled thereto. This
largeness in size adds to packaging problems within the doors thereby
reducing occupant shoulder room. These motors also add unnecessary weight
which adversely affects the vehicle's gas/mileage performance.
An alternative gear design that has been used is a compliant gear having a
rigid one-piece hub and web, and a separate rim member with a rubber-like
insert or ring located between the outer radial edge of the web and the
inner radial edge of the rim. An example of this configuration is
disclosed in U.S. Pat. No. 2,307,129 entitled "Shock Proof Gear", issued
to Hines et al. on Jan. 5, 1943, which is incorporated by reference
herewithin. Although the rubber-like insert of Hines is supposed to dampen
audible vibrations and somewhat reduce resultant stresses within the gear,
under load the rim is capable of compressing one side of the rubber-like
insert such that the rotational axis of the rim could become axially
offset from the rotational axis of the hub. This misalignment can cause
partial or complete disengagement of the gear teeth of the compliant gear
from those of its mating gear. In addition, gears having this type of
rubber-like insert strictly between the web and the rim are subject to the
rim torquing away from the hub in a transverse direction normal to the
direction of rotation. Under load this transverse movement may also cause
misalignment of the mating gear teeth which will localize stresses upon
distinct portions of each tooth. Moreover, the hub and rim may not provide
an adequate attachment, and thus force transfer, surface for the
rubber-like insert in extreme torque situations. A similar design using
elastomeric laminates with a shim therebetween is disclosed in U.S. Pat.
No. 4,674,351 entitled "Compliant Gear", issued to Byrd on Jun. 23, 1987.
Another compliant rotating member configuration is disclosed in FIG. 8 of
U.S. Pat. No. 3,216,267 entitled "Rotary Motion Transmitting Mechanism For
Internal Combustion Engines And The Like", issued to Dolza on Nov. 9,
1965. The Dolza sprocket/gear design contains a stamped cup-shaped hub
which has an outward radially extending flange and a cushioning member
fully attached to the side thereof. The rim of the sprocket/gear has a
generally L-shaped cross section with the radial inward leg being fully
attached to the opposite side of the cushioning member. In that design
there are gaps between the outer circumference of the cushioning member
and the inside radial surface of the rim and also a gap between the
radially inward surface of the cushioning member and the radially outward
horizontal edge of the cup-shaped hub section. While the sprocket/gear is
designed to maintain angular torsional rigidity while having radial
flexibility, under load the rim of the sprocket/gear may become elliptical
and thus encroach upon the gaps created above and below the cushioning
member. Moreover, the rotational axis of the rim may also become offset
from the rotational axis of the hub under working conditions.
It is also known to provide a sunroof motor with a conventional gear having
a unitary polymeric rim, offset web and hub. This gear further has a
receptacle and an inner set of rim channels for receiving a metallic cup
in an interlocking fashion. A Belleville washer frictionally rides against
an outer surface of the metal cup and is interlocked to a pinion shaft.
The gear is also journalled freely about the shaft. The amount of
frictional force exerted by the Belleville washer against the cup is
controlled by the amount of torque supplied to a pinion shaft engaging
nut; thus, the Belleville washer acts as a clutch mechanism. However, this
traditional sunroof motor is not provided with a rotational stress
dissipating structure beyond the coaxial Belleville washer. This sunroof
motor and gear system also suffers from being large in transverse size and
heavy in weight.
Furthermore, many conventional clutches employ rotation dampening devices
and spring biasing devices. For instance, reference should be made to the
following U.S. Pat. No.: 5,333,713 entitled "Friction Clutch" which issued
to Hagnere et al. on Aug. 2, 1994; U.S. Pat. No. 5,322,141 entitled
"Damped Driven Disk Assembly" which issued to Szadkowski on Jun. 21, 1994;
U.S. Pat. No. 5,310,025 entitled "Aircraft Brake Vibration Damper" which
issued to Anderson on May 10, 1994; U.S. Pat. No. 5,308,282 entitled
"Pressure Plate for a Vibration Damper Assembly having Built-In Lash"
which issued to Hansen et al. on May 3, 1994; U.S. Pat. No. 5,273,145
entitled "Hydraulic Clutch Control Means, In Particular For A Motor
Vehicle" which issued to Corral et al. on Dec. 28, 1993; U.S. Pat. No.
5,186,077 entitled "Torque Variation Absorbing Device" which issued to
Nakane on Feb. 16, 1993; U.S. Pat. No. 5,161,660 entitled "Clutch Plate
with Plural Dampers" which issued to Huber on Nov. 10, 1992; RE Pat. No.
34,105 entitled "Internal Assisted Clutch" which issued to Flotow et al.
on Oct. 20, 1992; and U.S. Pat. No. 4,996,892 entitled "Flywheel Assembly"
which issued to Yamamoto on Mar. 5, 1991; all of which are incorporated by
reference herewithin. While many of these clutch constructions recognize
an unsatisfied need for rotational stress reduction devices therein, and
propose various supposed improvements therein, further improvement in
performance, cost and assembly would be desirable. For example, the
rotationally oriented compression springs utilized in some of these
constructions can be easily overcompressed beyond their elasticity limit,
thus, leading to poor subsequent performance. By themselves, these
compression springs are not well suited for repeated, high load, full
compression.
SUMMARY OF THE INVENTION
In accordance with the present invention, the preferred embodiment of a
rotatable apparatus includes a pair of rotatable members joined by a
stress dissipating structure. The stress dissipating structure can be
employed in a gear, sprocket, clutch or the like. In one embodiment of the
present invention, antibuckling plates generally spanning between a hub
and rim define a hollow cavity. In another embodiment of the present
invention, the stress dissipating structure includes specifically
configured sets of nodules moving with the hub and rim. An additional
aspect of the present invention provides a stress dissipating structure
employing various anti-buckling plate attachment constructions. In still
another embodiment of the present invention, a uniquely sized and packaged
gear, gear housing and/or motor are employed in order to maximize output
force per pound of material efficiencies. An additional advantage of the
present invention over conventional systems is that the present invention
allows for a worm drive system coupled to a pinion gear to be vastly
improved regarding weight and size and, hence, power density (i.e., pounds
torque achieved per pound of material utilized). This is realized by
recognizing that torque is directly proportional to force times distance
and to horsepower divided by speed. Thus, by using a reduced size motor
with worm gear attached to power a ring or driven gear with an integrally
attached pinion, power density efficiencies greater than 50% over
conventional systems are achievable.
The configurations of the apparatus of the present invention are
advantageous over conventional systems in that the present invention
allows the stress dissipating structure to absorb structural stresses
between the hub and the rim due to instantaneous shocks created by
apparatus rotational start-up or shut-down, cyclical fatigue, and/or
overload. Furthermore, the stress dissipating resilient structure,
especially when coupled with anti-buckling plates, provides significant
lateral planar rigidity thereby resisting angular torsional deformation in
a direction normal to the rotational axis between the rim and the hub
while also discouraging rotational axis misalignment between the rim and
the hub (i.e., the center to center distances between driven and drive
gears are always maintained). By matching the bulk torsional rigidity and
allowed torsional deformations of the stress dissipating structure, which
can be a function of its modulus of elasticity, its dimensional thickness,
or the specific formations chosen, to that of the output coupling
performance proportions, the beneficial characteristics of a conventional
single piece homogenous gear, sprocket and clutch are maintained while the
resilient structure acts to synergistically dissipate stresses between the
rim and the hub.
The apparatus of the present invention is also much thinner in a transverse
(or crosscar) direction than conventional apparatuses thereby providing
packaging benefits. Furthermore, the present invention is significantly
lighter in weight than conventional systems while still increasing the
output force per pound of material efficiencies. Additional objects,
advantages, and features of the present invention will become apparent
from the following description and appended claims, taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic side elevational view showing the preferred
embodiment of a stress dissipation apparatus of the present invention
employed in an automotive vehicle window lift mechanism;
FIG. 2 is a partially exploded perspective view showing the preferred
embodiment of the present invention stress dissipation apparatus;
FIG. 3 is a side elevational view showing the preferred embodiment of the
present invention stress dissipation apparatus, with portions broken away
therefrom;
FIG. 4 is a cross sectional view, taken along line 4--4 of FIG. 3, showing
the preferred embodiment of the present invention stress dissipation
apparatus;
FIG. 5 is an enlarged sectional view, taken within circle 5--5 of FIG. 4,
showing snap-fit attachments employed with the preferred embodiment of the
present invention stress dissipation apparatus;
FIG. 6 is an enlarged sectional view, taken within circle 6--6 of FIG. 4,
showing another snap-fit attachment employed with the preferred embodiment
of the present invention stress dissipation apparatus;
FIG. 7 is a diagrammatic side elevational view showing the relationship of
nodules within the preferred embodiment stress dissipation apparatus of
the present invention; and
FIGS. 7a and 7b are fragmentary cross-sectional views, taken along lines
7a--7a and 7b--7b, respectively, showing the relationship of the nodules
to the anti-buckling plates;
FIG. 8 is a diagrammatic view showing an alternate embodiment apparatus of
the present invention; and
FIG. 8a is a cross-sectional view, taken along line 8a--8a taken from FIG.
8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of a stress dissipation apparatus of the present
invention can be employed in combination with an automotive vehicle door 9
window lift regulator or mechanism 11 as is shown in FIG. 1. In this
window lift application, the stress dissipation apparatus includes a
fractional horsepower dc electric motor 13 which drives a driven gear 15
coupled to a scissor arm linkage. The scissor arm linkage raises and
lowers a window 17 coupled thereto. The stress dissipation apparatus of
the present invention can also be employed with other types of automotive
window lift mechanisms such as, for example, that disclosed within the
following U.S. Pat. No.: 5,351,443 entitled "Automotive Door with Window
Pane lifter Module" which issued to Kimura et al. on Oct. 4, 1994; U.S.
Pat. No. 5,255,470 entitled "Vehicle Door Glass Regulator" which issued to
Dupuy on Oct. 26, 1993; U.S. Pat. No. 5,226,259 entitled "Automotive Door
with Power Window" which issued to Yamagata et al. on Jul. 13, 1993; U.S.
Pat. No. 4,222,202 entitled "Automotive Tape Drive Window Regulator" which
issued to Pigeon on Sep. 16, 1980; and U.S. Pat. No. 3,930,339 entitled
"Window Regulator, Especially for Automobiles, with a Threaded Cable
Moving in a Guide" which issued to Jander on Jan. 6, 1976; all of which
are incorporated by reference herewithin.
Now referring to FIGS. 2 and 3, electric motor 13 includes an armature or
motor housing 31, an armature 33, an armature shaft 35, permanent fixed
magnets 37, a commutator 39 and a brush card assembly 41. Armature 33
includes copper wire windings 43 wrapped inside of a plurality of armature
pack slots which are juxtaposed between a plurality of magnetically
conductive armature teeth 45. A helically wound worm gear portion 47 is
located upon armature shaft 35. Worm gear portion 47 is juxtaposed within
a worm housing portion 49 of a driven gear housing 61. Armature housing 31
has a longitudinal dimension "D.sub.L " and transverse dimensions
"D.sub.T." When electric motor 13 is installed in door 9 (see FIG. 1), the
crosscar transverse dimension of motor 13, the lateral direction of driven
gear housing 61 and the lateral direction of driven gear 15, are all taken
in a direction that is perpendicular to the plane of the side views shown
in FIGS. 1 and 3.
While electric motor 13 may have a variety of configurations and
components, the electric motor illustrated as part of the present
invention stress dissipation apparatus has similar characteristics to that
disclosed in U.S. Pat. No. 5,440,186 entitled "Motor with Isolated Brush
Card Assembly" which issued to Forsell et al. on Aug. 8, 1995, and is also
incorporated by reference herewithin. However, as will be further
discussed hereinafter, the electric motors of the present invention and of
U.S. Pat. No. 5,440,186 have significantly differing sizes and weights due
to the driven stress dissipating gear 15 and driven gear housing
constructions of the present invention.
Referring to FIGS. 3 and 4, driven stress dissipation gear 15 includes a
hub 71, a first annular antibuckling plate 73, a second annular
antibuckling plate 75, a rim 77 and a rotational stress dissipation device
79. All of these driven gear elements rotatably surround a driven gear
rotational axis 81. First antibuckling plate 73 is integrally molded as
part of a laterally offset wall of hub 71 while second antibuckling plate
75 is integrally molded as part of a section of rim 77. An auxiliary hub
91 is integrally formed from an end of second antibuckling plate 75
opposite that of an edge adjoining rim 77. Lateral edges of auxiliary hub
91 are provided with rounded corners to minimize surface area contact
against the adjacent first antibuckling plate 73 and driven gear housing
61. A radially projecting annular foot 93 inwardly depends from a median
portion of an auxiliary hub internal surface 95. A curved edge 97 of foot
93, curved edge 99 of auxiliary hub 91, and a curved end 101 of a finger
103 laterally project from rim 77 and act as bearing surfaces against
driven gear housing 61. An inner surface 111 of hub 71 also has a pair of
curved fingers 113 which act as bearing surfaces against driven gear
housing 61.
A generally cylindrical leg 131 inwardly extends, in a lateral direction,
from an inside face 132, of first antibuckling plate 73. A pointed barb
135, outwardly extending from a distal end of leg 131, engages a V-shaped
receptacle 135 disposed in auxiliary hub 91. Barb 133 and receptacle 135
achieve a snap-fit attachment between antibuckling plates 73 and 75. This
can best be observed by reference to FIG. 6.
Returning to FIG. 4, an outer edge 141 of first antibuckling plate 73 is
placed in snap-fit engagement within a V-shaped receptacle 143 of rim 77.
Thus, first antibuckling plate 73 is prevented from laterally moving
relative to rim 77 while first antibuckling plate 73 can be rotated
somewhat independently of rim 77.
As can be observed in FIGS. 2 and 3, rim 77 has a set of geared teeth 145
outwardly projecting therefrom for engagement with worm gear portion 47 of
motor 13. Additionally, as is shown in FIGS. 2 through 5, a steel pinion
gear 147, having outwardly extending spur gear teeth 149, is pressfit or
otherwise affixed upon an outer surface 151 of hub 71. A knurled pattern
may be provided upon an interior surface of pinion gear 147 to ensure
proper frictional engagement with hub 71. Pinion gear 147 may also be
attached to hub 71 through sonic welding, remelting of the hub through
pinion gear heating or the like. Hub 71, first antibuckling plate 73,
second antibuckling plate 75 and rim 77 are all preferably injection
molded from an engineering grade thermoplastic material such as
polyacetyl, a modified PBT, or a modified polyamide.
FIGS. 2, 4 and 5 illustrate driven gear housing 61 as being an injection
molded engineering grade material (or alternately, suitable die cast
metals such as zinc, aluminum or magnesium) with a cup-shaped cross
section defined by a generally cylindrical interior wall 171, a generally
cylindrical exterior wall 173 and a generally annular bottom wall 175. An
inner surface of interior wall 171 defines a substantially cylindrical
opening 181. As can be observed in FIG. 4, cylindrical opening 181 has a
diameter "D.sub.O " relatively larger than a radial distance "D.sub.G " of
one side of the gear (i.e., the difference between the radii of the rim
and the hub). Therefore, even though the present invention gear has a much
larger outer diameter as compared to conventional gears, the enlarged
cylindrical opening 181, coupled with a slightly thinner lateral dimension
in combination with a proportionally reduced motor size, result in overall
weight reduction as compared to conventional gears and drives.
Returning again to FIGS. 2, 4 and 5, an injection molded polymeric cover
plate 201, having an annular configuration, is screwed onto flanges (not
shown) with bosses extending from exterior wall 173 of driven gear housing
61. A flexible moisture seal, such as a nylon or teflon O-ring may be
employed between an inner edge of cover plate 201 and the adjacent
antibuckling plate 73. An injection molded polymeric retaining plate 203
is attached to interior wall 171 of driven gear housing 61 through a
pointed snap-fit barb 205 disposed along a side leg mating with a V-shaped
receptacle 207. Along an adjoining perpendicular top leg of retaining
plate 203, there is a laterally oriented and pointed snap-fit barb 209
which slidably engages into a V-shaped receptacle 211 of a distal edge of
hub 71. A sealing O-ring or the like may be provided between retaining
plate and driven gear housing 61 or between retaining plate 203 and hub
71.
Within the gear, a hollow and substantially annular cavity 221 is bordered
by first antibuckling plate 73, auxiliary hub 91 of second antibuckling
plate 75, foot 93 of second antibuckling plate 75 and interior wall 171 of
driven gear housing 61. Other hollow and annular cavities 223 and 225 are
also provided between portions of second antibuckling plate 75 and driven
gear housing 61. All of these cavities further contribute to the weight
reduction achieved by the present invention system while also allowing for
their bordering plate segments to act as a strong box-like structure.
Rotational stress dissipation device 79 is best illustrated in FIGS. 4 and
7. A first set of nodules 301 radially extends outward from an inner
member defined as either a modified form of the hub or the first
antibuckling plate. A second set of nodules 303 radially extends inward
from an outer member defined as the rim or the second antibuckling plate.
Each first nodule 301 has a proximal end 305 with a relatively constricted
rotational direction dimension as compared to an expanded rotational
direction dimension disposed at a distal end 307. Tapered surfaces 309 and
311 extend between the proximal and distal ends.
Second nodules 303 have a distal end 321 with a relatively constricted
rotational direction dimension as compared to an expanded rotational
direction dimension disposed at a proximal end 323. Tapered surfaces 325
and 327 extend between the proximal and distal ends. An elastomeric
material 341 such as Santoprene.RTM. 55 acts as a resilient member
disposed between the first and second sets of nodules 301 and 303,
respectively, for reducing differential rotational movements between the
hub and rim. Elastomeric material 341 can be injection molded or,
alternately, reaction injection molded in-place with the hub 71 and rim 77
preassembled or elastomeric material 341 can be separately molded and then
manually inserted between the hub 71 and rim 77. While the resilient
member is preferably shown as being elastomeric material, it may
alternately comprise springs, flexible spokes or the like. The design
structure employed with the present invention allows for utilization of
increased diameter driven and pinion gears in combination with smaller
electric motors. This results in overall reduced weight and provides for
improved dynamics with worm gear, driven gear and pinion gear speeds being
drastically reduced. These reduced gear speeds provide for, in addition to
other things, reduced wear, quietness and shock loads.
The amount of taper of each of the nodules 301 and 303 and the amount of
elastomeric material ("E") disposed between each pair of adjacent nodules
301 and 303 can be generally characterized by the following formula:
##EQU1##
where E.sub.2 is a rotational direction dimension between the proximal end
of one of the second set of nodules and the distal end of an adjacent one
of the first set of nodules;
E.sub.1 is a rotational direction dimension between the distal end of the
one of the second set of nodules and the proximal end of the adjacent one
of the first set of nodules;
D.sub.2 is a diameter of the rim teeth 145; and
D.sub.1 is a diameter of the hub teeth 149;
whereby generally uniform strain is imparted upon the elastomeric material
79 during deformation due to differing rotational movement between the rim
77 and the hub 71.
An alternate embodiment enlarged diameter driven gear can also be employed
in combination with the reduced size motor. In this embodiment a single
web spans between an integrally formed hub and web. Thus, the hub, web and
rim all rotate the same amount as a solid gear. Due to the enlarged driven
and pinion gear diameters, a stress dissipating structure may not be
required since the gears will rotate at significantly slower speeds and
thus be less susceptible to shocks and stress. Since the cylindrical
opening within the driven gear housing is of a large size, overall part
weight is minimized. The driven and pinion gears can be die cast from a
metallic material or can be injection molded from a reinforced nylon or
reinforced polyester polymeric material.
The following Table 1 sets forth the theoretical values and sizes of a
selected present invention system as compared to an existing conventional
automotive window lift system. It is significant to note that the total
system weight reduction is 300 grams (approximately 30% less than
conventional systems) while the overall system output torque is
maintained. Thus, very significant efficiencies in power density are
achieved (i.e., 61 inch-pounds per pound for traditional systems versus 91
inch-pounds per pound for one version of the present invention; this
amounts to greater than 50% improvement) while the lateral size and system
weight are reduced. Furthermore, due to the smaller motor size (e.g.,
requiring less copper wire windings, smaller permanent magnets and the
like) very significant cost savings are also achieved.
TABLE 1
______________________________________
CONVENTIONAL PRESENT INVENTION
SYSTEM SYSTEM
______________________________________
Electric Motor
Weight = 525 grams*
Weight = 200 grams*
and Armature
Armature housing length =
Armature housing size =
Housing 23/4 inches (D.sub.L) .times. 2
11/2 inches (D.sub.L) .times. 11/2
inches (D.sub.T)
inches (D.sub.T)
Worm RPM = 6000-8000
Worm RPM = 2400
Motor horsepower = 0.25
Motor horsepower =
0.041
Worm Gear Driven gear housing
Driven gear diameter =
Portion and
diameter = 2.5 inches
4.8 inches
Worm Housing
Weight = 275 grams
Weight = 325 grams
and Driven Gear
Housing
Driven Gear
Diameter = 2.4 inches
Diameter = 4.9 inches
Weight = 95 grams
Weight = 45 grams
Pinion Gear
Diameter = 9/16 inch
Diameter = 4 inches
Weight = 30 grams
Weight = 55 grams
System Torque
125 inch-pounds 125 inch-pounds
Total Weight
925 grams 625 grams
______________________________________
The following formulas, Table 2, and discussion thereafter, are designed to
allow one skilled in the art to utilize the present invention in systems
having various sized driven gears, pinion gears and output torques:
Horsepower=[(Torque)(RPM)]/Constant
Horsepower=[(Torque)(RPM)]/63025, where torque is measured in inches-pounds
.
Torque=(Distance)(Force).
TABLE 2
__________________________________________________________________________
EXEMPLARY
GEAR NO. 1 2 3 4 5 6
__________________________________________________________________________
WEIGHT (GRAMS)
925 775 725 750 625 575
WINDOW SPEED*
20 20 20 20 20 20
(FEET/MINUTE)
PINION GEAR** RPM
125 625 62.5 27.7 20.8 13.3
PINION GEAR**
9 18 18 32 54 72
NO. OF TEETH
DRIVEN GEAR - RPM
125 62.5 62.5 27.7 20.8 13.3
DRIVEN GEAR 2.4 2.4 2.4 3.6 4.8 6.0
DIAMETER (INCHES)
DRIVEN GEAR -- 0 0 50 100 150
DIAMETER %
INCREASE
WORM GEAR - RPM
7200 3650 3600 2400 2400 1920
MOTOR 0.248
0.124
0.124
0.055
0.041
0.026
HORSEPOWER
PINION GEAR 125 125 125 125 125 125
TORQUE
(INCHES-POUNDS)
__________________________________________________________________________
Gear No. 1 A conventional arrangement as listed in Table 1.
Gear No. 2 A solid hub, web, and rim arrangement (as shown in FIG. 8)
with the pinion gear size increased and the motor horsepower reduced.
Gear No. 5 The present invention as listed in Table 1 and shown in FIGS.
2-4.
Gear Nos. 3, 4, 5, 6 The present invention with a gear having a hollow
hub with annular spacing as shown in FIGS. 2-4.
*Approximate Speed
**Note all gear teeth have identical size and shape.
The present invention system, which employs the enlarged diameter driven
and pinion gears 147 in combination with the reduced size motor 13, is
also well suited for automotive vehicle powered moving panels such as door
windows, sunroof windows, sliding minivan doors or the like. These powered
moving panels must meet FMVSS 118 which mandates that the motor must stall
at twenty-two pounds of force in order to prevent occupant finger
pinching. Therefore, as can be observed in FIG. 8, an electrical current
sensor 401 is electrically connected to commutator 39 of motor 13 by way
of brushes for sensing if a sudden current rise is present (excluding
initial energization and deenergization current spikes) which indicate
that the closure force and motor torque has increased. Thus, the motor can
be deenergized and/or reversed. Sensor 401 can be a voltage divider,
resistor or the like, which operates in conjunction with a mosfet or
microprocessor electrically connected therewith. An enlarged diameter
("D.sub.DG ") of driven gear 403 and an enlarged diameter ("D.sub.P ") of
pinion gear 405, shown in FIG. 8 as having a solidly and integrally formed
hub 407, laterally central web 409 and rim 411, allow for slower
rotational speeds of the gears 403 and 405 and commutator 39. These slower
rotational speeds further provide the ability to more accurately sense
motor induced current rises as a relation of time and panel movement
distance. Depending upon the specific application, the larger diameter
gears 403 and 405 and smaller motor 13 are sized in accordance with the
theoretical calculations of Table 1.
Referring to FIGS. 2 and 8, the size relations of the driven gear 403 and
motor 13 can be characterized as follows:
D.sub.DG <(1.5)(D.sub.P), where "D.sub.P " is the diameter of the pinion
gear 405. Accordingly, an outer diameter D.sub.DG of the driven gear 403
is less than one and one-half times the outer diameter D.sub.P of the
pinion gear 405 while the relationship between the armature housing volume
divided by the outer diameter D.sub.DG of the driven gear 403 is less than
two inches squared. Although it is preferable to provide a large
cylindrical opening 181 (see FIG. 4) within the driven gear housing 61 and
hub 71 in order to save weight, it is also envisioned that the presently
discussed alternate gears may not necessarily need this opening to realize
the size and speed relationships and advantages of the present invention.
While the preferred embodiment of this stress dissipation apparatus has
been disclosed, it will be appreciated that various modifications may be
made without departing from the present invention. For example, the nodule
construction disclosed can be employed with other hub and rim
configurations. Furthermore, the pinion gear teeth 149 can be integrally
formed upon the hub 71. Also, the hub 71 need not be necessarily offset
from the rim 77. A more centralized web may alternately be employed
between the hub and rim, instead of outer antibuckling plates, while
harnessing the other novel aspects of the present invention. Many other
snap-fit means, such as separated cantilevered beams, tongue and groove
formations, dovetail formations, rounded barbs or squared barbs can also
be provided. Various materials have been disclosed in an exemplary
fashion, however, other materials may of course be employed. It is
intended by the following claims to cover these and any other departures
from the disclosed embodiments which fall within the true spirit of this
invention.
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